1. Field of the Invention
This invention relates to diamond insert drag bits.
More particularly, this invention relates to diamond faced insert studs and a method to press these studs into insert holes formed in the face of a drag bit body without damage to the diamond cutting tip of the studs.
2. Description of the Prior Art
Conventional synthetic diamond blanks typically are cemented, brazed, or sintered to an insert stud. The diamond layer is generally composed of a polycrystalline material joined to a substrate layer of tungsten carbide material. A synthetic diamond blank of the above description, for example, is manufactured by the Specialty Material Department of General Electric Company of Worthington, Ohio. The synthetic diamond blank goes by the trademark name of Stratapax drill blanks. The Stratapax blanks are typically brazed to the top extended portion of the studs. The blanks are brazed to the studs with about a 20.degree. angle of the diamond face relative to the axis of the body of the insert stud. State of the art stud insertion practice often damaged or destroyed this type of insert by attempting to drive the stud into its respective hole by pressing on the angled top surface of the cutting end of the stud. The stud hole in the drag bit is drilled to provide an interference fit, therefore, considerable force is exerted on the tip of the stud more often than not, resulting in damage to the synthetic polycrystalline layer. Since the diamond studs are very expensive, a more satisfactory method was urgently sought to cut down on diamond insert losses.
The present invention incorporates a ledge, boss or shoulder between the base of the stud and the cutting face of the blank brazed to the stud to provide a datum surface for a specially designed tool to hydraulically press the studs into the holes formed in the face of the drag bit.
This invention provides a diamond insert configuration for use with, for example, steel bodied drag bit designs having substantial cutter stand-off which has adequate strength to withstand drilling forces and can be easily attached to the bit body by interference fitting without damaging the stud or attached diamond cutter blank while maintaining alignment of the stud in the process.